They consulted equine experts, farmers and a neighbouring police force, but detectives only solved the mysterious case of the plaited manes when they turned for help to an unusual source – a friendly warlock.

Horse owners in Dorset had become perplexed when they kept finding that the manes of their animals seemed to have been twisted into plaits.

At first some thought that the wind had by chance whipped them into shapes that seemed to have been created by a human hand. Another theory was that thieves were sizing horses up and plaiting the manes of those they wished colleagues to steal at a later date.

But after consulting a warlock, police in Dorset concluded the horses were being used in witch "knot magick".

It is not clear exactly how many horses have been targeted but at least a dozen are known to have been involved.

Horse owner Harriet Laurie from Bridport, Dorset, and a member of the Shipton Riding Club, said: "When one of my horse's manes was plaited it took me some time to unpick and the wind had whipped it into a sort of dreadlock, but underneath were three strands neatly plaited. It is most bizarre.

"Whatever it is there is a lot of fear and anxiety. I know of about 12 horses that have had it done."

Dorset police said there was no evidence that the horses, some of whom were kept in fields in very remote spots, were being eyed by thieves. A spokesman said that it appeared to be a "harmless tradition".

PC Tim Poole, who has investigated the incidents, said: "We have some very good information from a warlock that this is part of a white magic ritual and is to do with knot magick."

"It would appear that for people of this belief, knot magick is used when they want to cast a spell. Some of the gods they worship have a strong connection to horses so if they have a particular request, plaiting this knot in a horse's mane lends strength to the request. This warlock said it is a benign activity, albeit maybe a bit distressing for the horse owner."